Compressed air breaker



United States Patent COIVIPRESSED AIR BREAKER Haakon Forwald, Ludvika, Sweden, assignor to Allmanna Svenska Elektriska Aktiebolaget, Vasteras, Sweden, a Swedish corporation Application April 26, 1954, Serial No. 425,688 Claims priority, application Sweden April 28, 1953 4 Claims. (Cl. 200-81) The present invention relates to a compressed air breaker, which is distinguished by a very good extinguishing ability and simplicity in construction and is suitable for both high and low voltages. The invention is substantially characterized in that the breaker is provided with a compressed air container of insulating material, having sufiicient volume for accommodating the quantity of air necessary for extinguishing the are produced during the breaking without causing the pressure of the air to decrease below the value necessary for the extinction, whereat the container is continuously in communication with a source for compressed air of necessary pressure. Within this container the stationary contact of the breaker is arranged, while the movable contact thereof with its associated manoeuvre means and the blow-out opening from the container are arranged within a casing for the mechanism located in the wall of the container. The container may comprise one or more pairs of contacts belonging to one or more different phases. At relatively low voltages the container may be fixed directly to an earthed support, but at higher voltages the container is preferably arranged on a support consisting of one or more insulators. The operating of the breaking gaps and the blow-out valves respectively may be either performed by means of the compressed air within the container and by aid of an evacuation pipe, coming from the casing for the mechanism, or the contacts and the valves may be operated by separate compressed air, which is supplied through an operating pipe coupled with the casing for the mechanism.

According to one embodiment of the invention, the casing or the casings for the mechanism are fixed within the surface of a cylindrical container, while the stationary contact of every breaking gap is suitably supported within the container, but according to another embodiment of the invention, which is particularly suitable for smaller breaking efiects and for not too high voltages, the compressed air container is constituted by an insulating cylinder, within the mantle wall of which a bracket is provided supporting the stationary contact and the casing for the mechanism, which accommodates the operating means for the movable contact, and the blow-out valve is arranged on one end of said cylinder. Such an arrangement is shown in the accompanying drawing in Fig. 1, while Fig. 2 shows another embodiment of the casing for the mechanism with associated blow-out valve and operating means for the movable contact. The casing for the mechanism shown in Fig. 2 is supposed to belong to a circuit breaker, wherein the casing for the mechanism is fixed within the mantle wall of the container, but it may, of course, also be formed so thatit may be arranged in the same manner as the casing for the mechanism in Fig. 1.

In the drawing, 1 designates a box of sheet material serving as base support, to which a cylinder 2 of insulating material is fixed by a flange or a sleeve 3. The stationary contact 4 of the breaker is secured to a bracket 5 fixed on the mantle of the cylinder 2, said bracket being fixed on the cylinder 2 by a bolt 6 and a nut 7, which bolt furthermore serves as the one terminal of the breaker. On the upper end of the cylinder 2, a sleeve 8 is provided serving as a fixture for the casing for the mechanism 9. The other terminal 10 of the breaker is fixed in the sleeve 8. The movable contact 11 of the breaker has the shape of a cylinder, which is provided with a collar 12, the outer edge of which fits in a metal cylinder 13 fixed on the easing for the mechanism 9. 14 is a spring, which tends to hold the cylinder 11 in its lower position, so that its lower edge 15 engages the stationary contact 4. The movable contact 11 is fixed on a stem 16 passing through a hole within the manoeuvre piston 17 of the blow-out valve. The stem 16 is provided with a central boring extending from the outer side of the lower part of the contact 11 to the outer side of the stem 16 immediately below a valve disc 19 fixed on the upper end of the stem. On the upper side of the valve disc 19 a pin 20 is fixed, which supports on its upper end a mark 21 movable within a transparent cap 22, thereby indicating the position of the movable contact with respect to the stationary contact, 1. e. whether the breaker is open or closed. The valve casing 9 is, on its upper end, provided with a shoulder 23, which is tightly engaged by the valve disc 19, when it is in its uppermost position. The space inside the sealing edge or the shoulder 23 communicates through the pipe line 24 with the manoeuvre valves arranged in the base box 1. The valve means of the blow-out valve consists of a piston 17, the lower cylindrical part of which slides against the sealing ring 25 within the casing for the mechanism 9. The valve piston 17 is, on its upper part, provided with a flange 26, on its lower part having a gland 27, which engages, when the valve piston is in its lower position, a sealing edge 28 within the easing for the mechanism 9. Said casing 9 is provided with blow-out openings 29, and outside these openings there are shields 30, for upwardly guiding the gases, which stream out from the breaker. The valve piston 17 is normally held in its lower position by the pressure acting on the upper side of the piston, and the spring 31.

The breaker is operated by aid of the press buttons 32 and 33, by which a circuit is closed from the operating battery 34 either through the operating coil 35 or the release coil 36 within the release magnet 37. Normally, the cylinder 2 is maintained filled with compressed air from the pipe 38 through the channel 39. If the release button 33 is pressed, the winding 36 is traversed by a current, whereby the release magnet 37 is demagnetized and the spring within the cylinder 40 moves the stem 41 upwards, thereby raising the stem 42, so that the valve disc within the cylinder 43 closes the outlet from the pipe 38 and brings the pipe 24 instead in communication with the open air.

At the evacuation of the pipe 24, the pressure existing within the cylinder 2 will force the movable contact 11 upwards against the action of the spring 14, and simultaneously also the valve piston 17 is moved upwards against the action of the spring 31. When the valve piston 17 moves upwards, the lower edge thereof leaves the conical sealing surface 44 within the casing for the mechanism, so that air may stream upwards from the cylinder 2 through the lower opening within the movable contact 11 and out through the blow-out openings 29. The upward movement of the valve piston 17, however, is limited by the fact that the flange 26 strikes the shoulder 45 within the casing for the mechanism, while the movable contact continues its movement upwards, until the valve disc 19 tightly engages the shoulder 23. As soon as the upper opening of the channel 18 has moved above the surface of the piston 17, the compressed air streams upwards through the channel 18 and fills the space below the valve disc 19, actuates the piston 17 and moves it gain downwards, so that the blow-out valves are closed again. The result of the release operation is, therefore, that the contacts are separated from each other and re rain in the open position, while the blow-out valve is opened for being closed shortly afterwards, during which interval the arc has time for being extinguished.

For the closing of the breaker, the press button 32 is pressed, so that the operating coil 35 is traversed by current, whereat the stem 46 is raised against the action of the spring Within the cylinder 47, whereby the lower valve disc on the stem 46 tightly engages the flange 43, while the upper valve disc within the cylinder 47 leaves the sealing edge 49, so that compressed air from the pipe 38 streams into the upper part of the cylinder 40 and presses down its piston 50, the stem 42 being carried downwards by the spring within the cylinder 43, so that a communication is opened from the pipe 33 to the pipe 24-.

The compressed air supplied through the pipe 24 acts on the valve disc 19, so that it leaves the sealing shoulder 23, and it now compressed air is supplied to the space above the valve piston 17, the movable contact 11 is moved downwards by the spring 14.

In the breaker, shown in Fig. l, the closing is performed by supplying compressed air to the manoeuvre pipe, while the opening of the breaker is performed by evacuating the manoeuvre pipe. In the breaker, shown in Fig. 2, the condition is modified in that the opening of the breaker is made by supplying compressed air to the manoeuvre pipe 24. In Fig. 2, the parts corresponding to the parts in Fig. 1 are designated by the same numerals. This arrangement Works as follows:

For opening the breaker, compressed air is supplied to the manoeuvre pipe 24, and this compressed air acts on the lower side of the flange 26 on the piston 17, so that it is moved upwards, its lower edge leaving the conical sealing surface 44 within the casing for the mechanism. As in Fig. l, the pressure in the container 2 acts on the movable contact 11 and moves it upwards against the action of the spring 14, until the valve disc 19 tightly engages the shoulder 23. The piston 17 moves upwards, until its movement is limited by the shoulder 45 within the casing for the mechanism, but when compressed air from the pipe 24 streams over the throttle valve 51 into the space above the piston 17, the spring 31 is able to move the piston 17 downwards, until the blow-out openings 29 are closed again. The movable contact 11, however, remains in its upper position, whereat the valve disc 19 engages the sealing shoulder 23. When then the breaker is to be closed, the pipe 24 is evacuated, and the air above the piston 17 streams out through the return 4 valve 52, and if the pressure then decreases in this space, the spring 14 is able to move the movable contact downwards into contact with the stationary contact 4.

The invention is, of course, not limited to the manoeuvre arrangements shown in the drawings for the movable contact and the blow-out valve, because these arrangements may be modified in different manners. The principal features of the invention are that the contacts of the breaker are arranged within a container, which is in continuous communication with a supply source for compressed air and that the movable contact and the blow-out valve are arranged within a casing for the mechanism, being detachably placed Within the wall of the compressed air container.

1 claim as my invention:

1. A compressed air circuit breaker comprising an electrically insulated compressed air container having a capacity sutficient to contain a volume of air with a pressure necessary for one extinction, means whereby the container is in continuous communication with a source of compressed air, fixed and movable breaker contacts located in the container, a casing detachably mounted on the container, a valve disc connected to the movable contact and located in said casing, a pipe line for the supply of operating air to said casing and for the escape of air from said casing, an air space in said casing communicating with said pipe line and a channel for the flow of the existing air from said container to said air space when the circuit breaker is opened.

2. A circuit breaker according to claim 1, comprising a spring acting upon the movable contact to move it into the closed position when air pressure is evacuated from said air space.

3. A circuit breaker according to claim 1, in which the movable contact is moved to its closed position by fluid pressure acting upon the said valve disc and supplied from said pipe line.

4. A circuit breaker according to claim 1, comprising a piston for the actuation of the movable contact, means whereby the air pressure existing in the container acts upon one side of the piston to open the contacts, and means whereby air pressure on the opposite side of the piston closes the contacts.

References Cited in the file of this patent UNITED STATES PATENTS 

